Amino-acids are essential for optimal health, as they form proteins and serve specific functions, such as assisting with food breakdown, aiding muscle growth and promoting tissue repair. They are divided into two categories: essential and non-essential amino acids. The 9 essential amino acids - histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine - cannot be naturally created so can only be sourced through food or supplementation. Non-essential amino acids – alanine, asparagine, aspartic acid and glutamic acid – can be generated within the body, so do not necessarily need to be sourced elsewhere. Arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine – can be beneficial when our health is impaired or when generally feeling unwell. A healthy balance of these is vital, particularly for athletes and sports people.